Process for the production of potassium sulphate and soda



Patented Jan. ,6, 1931 I UNITEDTSTATES P ENTJOF CARL THEODOR TrroRssELL, or cAssnL, GERMANY rnoonss non THE PRODUCTION or rorAssruivr s LrHA'rn ANDSODA No Drawing. Application filed February 25, 1930, Serial rm. 431,336, and in Germany lllarch 1929.

It is known that ammoniumsulphate reacts with alkali chlorides under certain conditionstoform ammonium chloride and alkali sulphates.

If sylvinite, which consists mainly of KCl and NaCl is stirred into a lye of a certain composition, which contains NH Gl, (NIL) gSO,

' and N11 glaserite and potassium chloride are obtained as deposited substances.

The essential point of the present process consists in conducting a self-containedprocess whereby the products potassium sulphate and soda are obtained, in such a way that a lye of above-mentioned composition is always recovered.

The lye must contain as much (NHQ SQ,

, as corresponds to the quantity of KCl in the crude salt. It is prepared from the mother liquor of an ammonia soda process, which is described more fully below. The composition of this mother liquor is given by the Solvay process. A mother liquor of this kind contains NaHCO NI-LOl and NILHGO or (NI-L) CO in addition to unconverted NaCl. It is known that calcium and strontium sulphate react with ammonium carbonate to 40 form ammonium sulphate and calcium or strontium carbonate. This reaction known per se requires a considerable time owing to the poor solubility of the two initial sulphates.

' The invention is based on the knowledge that the mother liquor from the Solvay process is very particularly suited for this reaction, because the solubility of calcium or strontium sulphate is increased in the presence of other salts, for instance chlorides and the reaction speed is thus accelerated. Ammonium chloride and sodium chloride act particularly favourably in this case (of. lgkglicgg, Volume II, section 2, pages 138 and p The Solvay mother liquor is stirred with so much. calciumor strontium sulphate, that the ammonium sulphate formed is equivalent to theKCl'contained in the crude salt. "The S olvay mother liquorhas a temperature adaptedto thisconversion, say 3040 C. and ,contains fif the usual type of crude sylviniticsalts is used as initial material, a substantial excess of ammonium carbonate, which promotes the rection. Q

In this operation the carbonate acid bound as bica rbonate is liberated and can be colle'ctedand re-introduced into. theprocess.

7 ,TheCaCO or SrGOg'formed is separated il-Ild a crudesylviniticsalt stirredintothe 1 ye. ,7 I .7 V p I Duringthis' stirring ammonia is introducedwhile at the same time cooling, the above-mentioned deposit consisting of glaserite and potassium chloride being obtained. 75 This-deposited substance is'separ ated and converted by treatment with water into solid potassium sulphate. I

Sodium bicarbonate is precipitated according to the Solvay process from the 80 mother'l'iquor fromthe formation of glaserateQ w i r In addition to some ammonium carbonate the mother iliquor contains mainly NaCl, NI-LCI and NH I ln order to be able to use this mother lye for the Solvay process, it must first be freed from any NI-LCl, which takes place simply by cooling. This cooling can be elfected wholly or partially by withdrawing by sucif the potassium sulphate obtained in such a case is used for a process in which calcium or strontium sulphate are formed.

Such a process is for instance the known decomposition of crude phosphate with a mixture of nitric acid and potassium sulphate.

The gypsum tassium sulphate process, and thus a comobtained in such a case is then re-introduced into the above described po- 'phate obtained by the process claimed in claim 1, for aprocess in which calcium or strontium sulphate is formed, and the use of these latter sulphates for producing further potassium sulphate according to the process claimed in claim 1, as set forth.

In testimony whereof I have signed my name tothis specification.

CARL THEODOR THORSSELL.

pletely self-containediprocess is. provided, in

Potassium si 'ilpliate :eonverted with strontium hydrate to potassium hydrate and strontium sulphate, in which case, as is known, a relatively strong solution otpotassiumhydrate -is' obtained, the resulting strontium sulphate is introduced, again into the above described'potassium sulphateprocess and the strontium carbonate, thus formed,

is converted into strontium oxide or hydrate, so that with the same employment of a completely self-contained cycle process the 7 products potassium"hydrate, soda and ammonium ChlOIldQ EtIfB prepared from sylvlmte, ammonia and carbonic acid, in which case sulphuric acid remaining in circulation.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be per- Iformed, I declare that what I claim v 1. A process for the production of potassium sulphate and soda from crude sylvinitic salt with calcium or strontium sulphate, consistingin mixing sodium bicar- 'bonate mother liquor obtained from the Solvay process with calcium or strontium sul- I phate, separating the carbonate formed,

treating the remaining liquor with crude sylvimtic potash salt and ammonia, separating the glaserite and potassium chloride formed, cooling the mother liquor for re- 7 moving the ammonium chloride contained therein, treating the remaining mother liquor by the Solvay process for the production of bicarbonate mixing the resulting mother liquor with calcium or strontium sulphate again, as and forthe purpose set forth.

2. A process for the production of potas i siumsulphate and soda from crude fsylvinitic salt with calcium or strontium sulphate, as claimed in claim-1 and in which the said mixture'of glaserite and potassium chloride is reated withwa er ior converti g the'same into potassium sulphate, as set forth.

31., Th temployment oi; the potassium sill- 7 Q 

